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In your timeline, drop the Clean Plate (footage without the mic physically in the shot) below the footage with the mask (the footage with that big gaping hole where the mic used to be).

Hey look! The mic is gone! Using this technique, you were able to get the mic close, thus maintaining good sound quality for the dialogue, without having to worry about keeping the mic out of the shot! Remember this while shooting, because the number one thing that people notice in a film is bad sound. Bad picture can oftentimes be excused, but that's not the case with sound. Keep your production value high, and your movie will benefit!

Yeah, you know you were waiting for this one... As we've mentioned before, you can go to www.detonationfilms.com for stock footage of explosions!

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You'll notice that part of the explosion is covering our actor (F).

Here's where the roto work comes in. We place our explosion layer on top of our live action footage shot, so naturally, it's going to be above (or covering) everything in the shot. In this particular scene, we want the explosion to happen behind the actor, so we have to do some roto work.

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Simply select the explosion layer, and cut a mask around the actor. You don't have to worry about the side that the explosion isn't reaching (the left side of the actor); you just want the actor's right side to cover the explosion. Select your Pen tool and draw a mask around the actor where the explosion needs to pass behind him. Make sure the mask is set to Subtract, so it subtracts the section you select.

Here's a shot of the mask I drew (G).

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Here's a shot of the screen without the mask lines showing (h). You can see that the actor now covers that part of the explosion, creating the illusion that it's behind him. We added a 2-pixel feather to the mask in order to make the edges blend better. Edges are not sharp in real life, so play with the feathering to see what works best. You can find the Mask Feather options by pressing MM on the keyboard with the layer selected.

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The only problem is that this mask is effective for only one frame. If you move to the next frame, the mask won't follow. You have to animate it to follow, or outline, the actor.

In this picture, I've moved 5 frames forward (I). You can see the results of not animating the mask. Part of the explosion is now covering our actor's head, and there is a gap between the actor and the explosion. Not good...

So here's the same shot but with the mask animated to follow the actor. (When I say "animate the mask," I mean moving the points of the mask so that the mask continually outlines our actor. You'll have to keyframe the Mask Path in order for After Effects to remember the different positions of the mask. See the Rotoscoping Tutorial video for more information.)

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Here, you'll notice that we have animated the mask to follow the outline of our actor (J). Notice the gap and the explosion covering his head are gone, and everything is as it should be.

Just animate the mask for the entire shot, and you will now have an explosion in the frame that stays behind the actor, giving the shot realism through correct depth.

I hope I didn't confuse you too much. This can be very involved and complicated material, but - trust me - it's well worth learning. You'll be able to do so much more, both technically and creatively! Watch our video to see what I mean.

As my favorite director always says, "If you're both technical as well as creative, you're unstoppable!" How do you think we shot that video in one day for no money? Until next time!

Click here to view the tutorial video for Rotoscoping.